Todd Macfarlane, a conservative rancher from Utah, chose not to vote for either candidate after getting his news from a liberal Facebook news feed at key points during the election.
Photograph: Sam Levin for the Guardian

The 2016 election took place under the spectre of a bubble. Not the subprime mortgage lending bubble that shaped the 2008 election, but the “filter bubble”. Tens of millions of American voters gets their news on Facebook, where highly personalized news feeds dish up a steady stream of content that reinforces users’ pre-existing beliefs.

Facebook users are increasingly sheltered from opposing viewpoints – and reliable news sources – and the viciously polarized state of our national politics appears to be one of the results.

Criticism of the filter bubble, which gained steam after the UK’s surprising Brexit vote, has reached a new level of urgency in the wake of Donald Trump’s upset victory, despite Mark Zuckerberg’s denial it had any influence.

To test the effects of political polarization on Facebook we asked ten US voters – five conservative and five liberal – to agree to take a scroll on the other side during the final month of the campaign.

We created two Facebook accounts from scratch. “Rusty Smith”, our right-wing avatar, liked a variety of conservative news sources, organizations, and personalities, from the Wall Street Journal and The Hoover Institution to Breitbart News and Bill O’Reilly. “Natasha Smith”, our left-wing persona, preferred The New York Times, Mother Jones, Democracy Now and Think Progress. Rusty liked Tim Tebow and the NRA. Natasha liked Colin Kaepernick and 350.org.

Our liberals were given log-ins to the conservative feed, and vice versa, and we asked our participants to limit their news consumption as much as possible to the feed for the 48 hours following the third debate, the reopening of the Hillary Clinton email investigation, and the election.

Not all of our participants made it through to election day. “You might as well have been waterboarding a brother,” said one of the participants, Alphonso Pines, after his first exposure to the right-wing feed.

But eight of our bubble-busters made multiple forays into the Facebook feed and were interviewed three or four times – one even said the experience influenced his final decision. Here’s how it impacted them all:

Inside the bubble

From Utah to St Louis, and Georgia to San Francisco, most of our participants were aware that they lived in a bubble.

“Twelve people have shared a story with me about the Hillary Clinton bus dumping human waste into the sewer system,” said Trent Loos, a farmer and radio host from central Nebraska. “I never see positive stuff about Hillary Clinton. I didn’t know that existed.”

Several participants said that they sought out opposing viewpoints outside of Facebook, by watching Fox News (for a liberal) or reading High Country News (for a conservative), but most had a generally one-sided experience within Facebook’s news feed.

“If I got any Trump supporters on my page, they’re in the closet,” said Pines, a retired union organizer and liberal who lives in Smyrna, Georgia.

‘Like reading a book by a fool’

If there was one thing that our participants agreed on, it was that the Facebook feed “the other side” reads is largely wrong.

“It’s like reading a book by a fool,” said Pines. “It’s hard to read something you know is a lie.”

Another liberal, Nikki Moungo from St Louis county, Missouri, went a step further: “It’s like being locked into a room full of those suffering from paranoid delusions,” she said.

Loos said that he found the left-wing Facebook feed was too “confined” and he was frustrated by the liberal media’s attempts to “spin” and “justify” every negative story about Clinton.

Andra Constantin, a conservative project manager from Westchester County, New York, was frustrated by “this whole big brainwashing push to save the world from the horrible climate change”.

Both Constantin and Green agreed that a conservative Facebook feed in the run up to the election had more diversity of opinions than a liberal one, largely because Republicans were divided on supporting Trump while liberals were generally united behind Clinton.

“I didn’t see the issues being discussed,” Constantin said of the liberal feed. “Even though we can be hateful and nasty, at both ends of the conservative side we’re talking about the issues a bit more.”

When Green returned to his regular liberal feed after the third debate, he felt completely out of the loop with his cohort’s topics of conversation. “I logged in and I was like – bad hombres, nasty women, what is everyone talking about?”

‘They hate me’

For several of our participants, reading the alternative Facebook feed was not just surprising, but hurtful.

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“It’s hard for me to read some of it,” said Pines, who is black. “It’s just a racist kind of thing, and I don’t think it’s cleverly disguised.” Pines was particularly pained by the way in which Obama was portrayed by the right-wing sources, which he described as “code” and “dog whistles”.

Pam Tau Lee, a retired community organizer and activist from San Francisco, also had difficulty stomaching the right-wing feed.

“Everything that they are saying is bad, I fall under that category,” said the fourth-generation Chinese-American. “The hateful stuff: that’s me. They hate me and my community and what I stand for.”

Pam Tau Lee, a retired community organizer from San Francisco. Photograph: Courtesy of Pam Tau Lee

Kathleen Matz, who owns a pet care service in Oakland, California, found the “misogyny” on sites like Breitbart “hurtful”.

“I just stopped. I couldn’t look at it anymore,” she said.

But it wasn’t only the liberals who found the experience painful.

“I’m seeing a lot more hate from the liberal side,” said Constantin. “It’s all about how much of a horrible, fascist, racist, misogynist Trump is.”

On her own feed, Constantin found herself winnowing down her friends in order to avoid arguments.

“I did unfollow a lot of friends because I didn’t want to feel enticed to correct what they were saying and get in a fight,” she said.

“Honestly, I hated it,” said Janalee Tobias, a longtime conservative activist and member of Mormons for Trump from South Jordan, Utah. “I’m seeing a psychiatrist trying to get over the shock and the hate from the left,” she joked. “I thought this would be easier for me to handle, because I’m considered pretty open minded.”

‘The needle moved’

For some of our participants, checking out the other bubble only confirmed their commitment to staying inside their own.

“I learned that [people on the right] are way more vicious and lack a certain maturity that I would expect of adults,” said Moungo, after the election. “This just absolutely confirmed it ... They are irredeemable monsters.”

“Seeing the liberal feed pulled me further to the right,” said Loos. “Without getting the counterpoint, I was drawn more and more to the conservative side. Instead of luring me in, it pushed me away.”

But some of our participants found greater understanding from the experiment.

Kathleen Matz (right), a liberal, found the ‘misogyny’ on sites like Breitbart ‘hurtful’. Photograph: Courtesy of Kathleen Matz

Lee said she was impressed by the “cleverness” of right-wing messaging, which uses “words like working class and jobs and economic stability. That promise is so great that it overshadows everything else, and I could see that, if that’s the only thing that I saw, I could understand. I could be swayed.”

Asked whether that understanding had resulted in her having more empathy for Trump voters, Lee said: “I don’t know if I’m there yet, but I’m working on it. I come from a place where I want to build a movement coming from love and compassion, so I’m working on it.”

One of our participants, Todd Macfarlane, said his time on the liberal Facebook page influenced his final decision. A rancher and attorney from Kanosh, Utah, Macfarlane is a registered Republican who was considering supporting the GOP nominee, but ultimately chose not to vote for any presidential candidate.

“The needle moved,” he said after his first exposure to the liberal feed. “I was kind of more undecided as I looked at it ... I was persuaded to think he’s a really bad choice.”

Macfarlane didn’t encounter any liberal news sources that convinced him to support Clinton, but his time on the feed helped him realize that a Trump presidency could be dangerous.

“It had to do with his overall temperament and decorum and demeanor,” he said. “It just reinforced for me the concern about what he might do with that much power.”

‘Maybe we should stop’

It wasn’t just his vote that changed, for Macfarlane. Since participating in the experiment, he said, “I’m a lot more interested in engaging with people who are open minded and are willing to talk about the whole picture.”

Nikki Moungo, a liberal from Missouri: ‘It’s like being locked into a room full of those suffering from paranoid delusions.’ Photograph: Courtesy of Nikki Moungo

Constantin, who currently relies on Facebook for 100% of her news, said that she has concluded that the platform “seems to filter out credible news articles on both ends and feed sensationalist far left/far right things”.

“I have to be more proactive about getting good quality content,” she said.

Tobias said that exposure to the other side made her realize how difficult it might be to find common ground after the election.

“It’s frightening to me to see how much the left and the right are divided right now,” she said. To bring us back together, I don’t know what it’s going to take.”

For Green, the lessons of the election are more stark.

“Maybe we should stop having social media,” he said. “For all the things that social media has done in terms of making it easier for me to stay in touch with someone that I was vaguely friends with in college, maybe the ability with social media for people to construct their own reality to create a mob is not worth it.”